Method for controlling rust

ABSTRACT

A combination comprising a multi-site contact fungicide, a first systemic fungicide and optionally a second systemic fungicide and a method using the same.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of U.S. patentapplication Ser. No. 15/673,311, filed on Aug. 9, 2017, which is aContinuation Application of U.S. patent application Ser. No. 15/039,463,filed on May 26, 2016, now U.S. Pat. No. 9,788,544, which is a nationalphase application under 35 U.S.C. § 371 of International Application No.PCT/IB2014/064891, filed on Sep. 27, 2014, which claims priority toIndian Patent Application No. 1336/KOL/2013, filed on Nov. 26, 2013; thedisclosures of all of which are hereby incorporated by reference intheir entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for the prevention and/ortreatment of phytopathogenic fungi. More particularly, the presentinvention relates to a method of using fungicides for the preventionand/or treatment of Asian soybean rust in leguminous plants.

BACKGROUND OF THE INVENTION

The fungus of the genus Phakopsora is known to infect legumes. Two mostprominent strains of the genus are Phakopsora pachyrhizi and Phakopsorameibomiae. Soybean rust caused by Phakopsora pachyrhizi is the mostdamaging disease affecting the yield of leguminous plants causingwidespread damage to crop and depleting yield from 10 to 90% if nottreated in time. Commonly known as Asian Soybean Rust (ASR), Phakopsorapachyrhizi infections must be detected early and treated early so as toprevent the geographic spread of the disease, which is airborne andcauses severe loss of yield. The disease spreads through spores calledurediniospores which are carried through the environs, resulting inwidespread damage. The disease earlier restricted to Asia and Australiahas spread to Africa and in the past two decades, spread to South andNorth America. The first detection in the Americas was in 2001 in SouthAmerica; from there it spread to North America where it was firstdetected in 2004.

Phakopsora pachyrhizi is known to infect over 30 legumes includingcommercially important edible beans as well as kudzu. The additionalhost crops serve as a reservoir for spores which can settle over thewinter on the host crops and then spread in warmer weather. Earlydetection and treatment of Phakopsora is very essential to prevent thespread of disease and the loss of yield. Fungicides typicallyrecommended for the treatment of this disease include Qo inhibitors(Quinone outside inhibitors), DM inhibitors (demethylation inhibitor),SDH Inhibitors (succinate dehydrogenase inhibitors). These fungicideswhen applied alone provided some control but, resistance was quicklyobserved, specifically in DM inhibitors (K Schmitz e al, Pest ManagementScience, Vol. 69, Issue 10 (2013)). Combination of Qo and DM inhibitorsare also known in the art for the treatment of the disease, however, thetreatment is not effective in controlling the disease and improvingyields at the same time. Also, resistance to DM inhibitors effectivelyrenders such combination compositions useless as the ASR strains caneffectively overcome the effects of DM inhibitors. Venancio et. al(Poster #24, 2011 Field Crops Rust Symposium) taught the use ofcombination of stroilurins (Qo inhibitors) and triazoles (DM inhibitors)for the treatment of ASR, the control of the disease was found to befavorable; however, yield was significantly low, and some combinationsshowed lower disease control and significantly poor yield. Older studieshave demonstrated the use of multi-site inhibitor fungicides such aschloronitriles and dithiocarbamate for the treatment of Soybean Rust;however, none of the multi-site inhibitor fungicides were successful inthe control of the disease or the increase in yield.

The most important factor in Soybean Rust is the loss of foliage thatresults in the loss of nutrients and decrease in the overall yield ofthe crop. Numerous papers have been published that demonstrate moderateincrease in yield with the application of fungicides. However, there isa need for a method of treatment that demonstrates improved yields alongwith preventive and/or curative capabilities in the treatment of SoybeanRust.

Compositions comprising the single actives used in the treatment of ASRhave demonstrated very little control as compared to combinations,however, the cost and concentrations of such combination fungicides usedin the treatment of ASR is significantly higher. There is therefore aneed in the art for a method of treatment that provides excellentcontrol over Asian Soybean Rust in host plants, as well as provides highyields, maintain nutrition and quality of the plants.

Hartman, G. L., Saadaoui, E. M, and Tschanz, A. T., Scientific eds.1992, Annotated bibliography of soybean rust (Phakopsora pachyrhiziSydow), A VRDC Library Bibliography Series 4-1, Tropical VegetableInformation Service. Taipei: Asian Vegetable Research and DevelopmentCenter, recommended the use of triadimefon, thiabendazole,chlorothalonil and certain ethylenebis-dithiocarbamates for the controlof soybean rust. The protection offered by triadimefon was inconsistent,in comparison to mancozeb, although it successfully prevented yieldlosses. However, triadimefon required frequent applications at 10-20 dayintervals, starting from the flowering stage in order to retain itseffectiveness. Thiabendazole was found to be less effective than certainethylenebis-dithiocarbamates, and further was found effective only whenused with oxycarboxin. Thiabendazole was also found to be phytotoxic.Chlorothalonii offered equal or worse rust control vis-a-vis the otherfungicides recommended in this paper.

The use of ethylenebis-dithiocarbamates such as mancozeb, zineb or manebalone has been found effective for the control of soybean rust whenapplied 7 to 21 days apart, provided the first application was madethree weeks after planting and continued as late as till the floweringstage. Moreover, not all the studied showed yield increase due to theindividual applications of ethylenebis-dithiocarbamates.

Oxycarboxin was found less effective than ethylenebis-dithiocarbamates,was found inconsistent in rust control and yield protection varied withthe particular study. Oxycarboxin is also required to be applied whenlesions first appear and then at 7—intervals for effective control,which is expensive and inconvenient.

Azoxystrobin is another fungicide, which has been recommended forsoybean rust control. However, it is known in the art that a single lateapplication of azoxystrobin does not control soybean rust or protectyield losses.

A recent survey by the present applicant found that a limited number ofabout 8-10 fungicides were approved to be used for the control ofsoybean rust, which are:

-   -   (A) Conazole type fungicides such as myclobutanil,        propiconazole, tetraconazole and tebuconazole;    -   (B) Strobilurin type fungicides such as azoxystrobin and        pyraclostrobin;    -   (C) Combinations of conazole and strobilurin type fungicides        such as propiconazole+trilfoxystrobin; and    -   (D) Ethylenebis-dithiocarbamates such as mancozeb.

Thus, additional fungicides are needed for soybean rust control due toeconomic reasons as well as for resistance management strategies.However, the choice of fungicides for soybean is not straightforward.

Soybean is not usually treated with foliar fungicides. Therefore, thechoice of a protective foliar fungicide leaves open the question of itsapplication methods or the effect of the particular selected fungicideon the crop. The pathogen for soybean rust is usually found on the lowerleaves of the plant where the lesion numbers increases as the inoculumbuilds up. As the plant begins to flower, this inoculum builds upincreases and the infection moves up the plant as the lower leaves dieoff and drop. The crop needs protection from flowering stage to the podfill stage, during which the plant canopy is very dense. The densecanopy is an effective barrier to penetration of fungicides applied overthe top of the canopy. Therefore, foliar fungicides are not preferredduring this stage of fungicidal control, or even the systemic fungicidesthat do not move down the plant system present a problem.

U.S. Pat. No. 8,044,084 discloses a method for controlling harmful fungiby applying a combination of a strobilurin fungicide with an ethylenemodulator. It was found that the host plants are damaged to a lesserextent than after the treatment with a customary fungicide.Specifically, this patent teaches a combination of pyraciostrobin withprohexadione-Ca in weight ratio of from 20:1 to 0.05:1.

US 2011/0312493 teaches a method for controlling Asian soybean rust. Themethod comprises treating a glyphosate tolerant soybean plantpropagation material with a fungicide selected from fiutriafoi,triticonazole, tebuconazole, ipconazole, epoxyconazole, orysastrobin,prothioconazole, fiuoxastrohin, azoxyscrobin, furametpyr, cyproconazoleand subsequently with glyphosate.

US 2008/0153824 discloses for controlling rust infections in leguminousplants by using orysastrobin or a mixture of orysastrobin with azoles,acylaianines, amine derivatives, anilinopyximidines, dicarboximides,dithiocarbmates, heterocyclic compounds, phenylpyrroles, cinnamides andanalogs thereof.

WO 2012/110464 discloses a method for controlling Asian soybean rust byapplying a succinate dehydrogenase inhibitor fungicide.

There is a need in the art for a fungicidal method of control of soybeanrust that takes into account the economics of fungicide application, thetiming and number of sprays and lastly, the choice of the fungicide foran effective control. These issues present a considerable challenge toan agronomist.

Moreover, the single fungicide treatment regimen for Asian Soybean Rust(ASR) has many drawbacks. Azoxystrobin was one of the first of the Qoinhibitors to be used for the treatment of soybean rust individually andit provided good control. However, according to FRAC guidelines,Azoxystrobin should be used more as a preventive fungicide rather than acurative fungicide. The risk of resistance to Qo inhibitors is also veryhigh. Another drawback is that even at the lowest labeled rate of useproduct, Qo inhibitor fungicide still costs the highest.

Alternatively, DM Inhibitors have shown good efficacy towards ASR,however, recent findings have suggested that Phakopsora pachyrhizi iscapable of developing resistance to DM inhibitors.

Combinations of Qo inhibitors and DM inhibitors are currently registeredin the Americas have demonstrated 40 to 60% control of ASR. However, thecontrol efficacy mixtures of DM inhibitors with Qo inhibitors havereduced in the past seasons. Also, there is no great increase in yieldand no decrease in the stress on the plant due to pest pressure.

Use of SDH inhibitors is also recommended for soybean rust control.However, single fungicides such as Boscalid offer only a moderatecontrol of ASR.

Dithiocarbamates, and mancozeb in particular, was one of the firstfungicides to be used for the treatment of ASR. Over the years manytrials have been conducted on the use of Mancozeb alone for thetreatment of ASR. However, the efficacy of mancozeb alone towardssoybean rust control requires further research.

The present invention aims to overcome the problems in the prior art,namely, the need for a method of treatment that will not renderPhakopsora resistant to actives, improve yield substantially and atreduced concentrations of actives, as well as reduced costs.

OBJECTS OF THE INVENTION

The present invention, described hereinafter, achieves at least one ofthe following objects of the invention.

It is an object of the present invention to provide a method to preventand/or treat Phakopsora pachyrhizi and/or Phakopsora meihomiae infectionin a host plant.

It is another object of the present invention to provide a method oftreating Soybean Rust in a host plant that boosts the nutrient level inthe plants and improves the quality of the plants.

It is another object of the present invention to provide a method oftreating Soybean Rust in a host plant such that the quantities offungicides used in the treatment is greatly reduced.

It is another object of the present invention to provide a method fortreating soybean rust in a host plant wherein the fungicides usedprovides a synergistic control of soybean rust.

SUMMARY OF THE INVENTION

In an aspect, the present invention provides an improved method oftreating soybean rust infection in a host leguminous plant, wherein theimprovement comprises treating the plant at the locus of the infectionwith a dithiocarbamate fungicide, and concurrently, prior orsubsequently to the dithiocarbamate fungicide, with at least anotherfungicide selected from a demethylation inhibitor, quinone outsideinhibitor, succinate dehydrogenase inhibitor, quinone inside inhibitoror combinations thereof.

In another aspect, the present invention provides a fungicidalcombination for treating soybean rust infection in a host leguminousplant, wherein the combination comprises a first dithiocarbamatefungicide, and at least second fungicide selected from a demethylationinhibitor, quinone outside inhibitor, succinate dehydrogenase inhibitor,quinone inside inhibitor or combinations thereof.

In another aspect, the present invention provides the use of adithiocarbamate fungicide as a synergist to improve disease control in ahost plant infected by soybean rust when applied subsequently, prior orconcurrently to at least another fungicide selected from a demethylationinhibitor, quinone outside inhibitor, succinate dehydrogenase inhibitor,quinone inside inhibitor or combinations thereof.

DETAILED DESCRIPTION OF THE INVENTION

It has surprisingly been found that the use of a contact protectivedithiocarbamate fungicide along with at least one systemic fungicideeffectively penetrates the dense canopy barrier of the infectedleguminous plant while simultaneously not allowing the rust pathogen tomove up the plant foliage. Without wishing to be bound by theory, it isbelieved that the contact protective dithiocarbamate fungicide componentof the combination effectively penetrates the dense plant foliage, whilethe systemic fungicide component effectively prevents the rust pathogenfrom infecting the remaining portion of the plant effectively reducingthe susceptibility of the plant towards the infection. This synergisticcomplementation was not seen when either the foliar protective fungicideor the systemic fungicide were individually used in isolation, but wasobserved when the two fungicides were used in conjunction. Thissynergistic complementation between the contact preventivedithiocarbamate fungicide and a systemic fungicide for the treatment andcontrol of Phakopsora species of fungicides was unexpected andsurprising.

Thus, in an aspect, the present invention provides a method for treatingsoybean rust in a host leguminous plant, wherein the method comprisestreating the plant at the locus of the infection with at least onemulti-site contact fungicide; and concurrently, prior or subsequently tothe multi-site contact fungicide, with at least one systemic fungicide.

The multi-site contact fungicides of the present invention inhibitfungal growth through multiple sites of action and have contact andpreventive activity. In an embodiment, the multi-site contact fungicidemay be selected from copper fungicides, sulfur fungicides,dithiocarbamate fungicides, phthalimide fungicides, chloronitrilefungicides, sulfamide fungicides, guanidine fungicides, triazinesfungicides and quinone fungicides.

The copper fungicides of the present invention are inorganic compoundscontaining copper, typically in the copper (II) oxidation state and arepreferably selected from copper oxychloride, copper sulfate, copperhydroxide and tribasic copper sulfate (Bordeaux mixture). The sulfurfungicides of the present invention are inorganic chemicals containingrings or chains of sulfur atoms and is preferably elemental sulfur. Thedithiocarbamate fungicides of the present invention contain adithiocarbamate molecular moiety and are selected from amobam, asomate,azithiram, carbamorph, cufraneb, cuprobam, disulfiram, ferbam, metam,nabam, tecoram, thiram, urbacide, ziram, dazomet, etem, milneb,mancopper, mancozeb, maneb, metiram, polycarbamate, propineb and zineb.The phthalimide fungicides of the present invention contain aphthalimide molecular moiety and are selected from folpet, captan andcaptafol. The chloronitrile fungicide of the present invention comprisesan aromatic ring substituted with chloro- and cyano-substituents and ispreferably chlorothalonil. The sulfamide fungicides of the presentinvention are preferably selected from dichlofluanid and tolylfluanid.The guanidine fungicides of the present invention are preferablyselected from dodine, guazantine and iminoctaadine. The triazinefungicide of the present invention is preferably anilazine. The quinonefungicide of the present invention is preferably dithianon.

In an embodiment, the multi-site contact fungicide of the presentinvention is a dithiocarbamate fungicide selected from amobam, asomate,azithiram, carbamorph, cufraneb, cuprobam, disulfiram, ferbam, metam,nabam, tecoram, thiram, urbacide, ziram, dazomet, etem, milneb,mancopper, mancozeb, maneb, metiram, polycarbamate, propineb and zineb.

Thus, in this aspect, the present invention provides a method fortreating soybean rust in a host leguminous plant, wherein the methodcomprises treating the plant at the locus of the infection with at leastone dithiocarbamate fungicide selected from amobam, asomate, azithiram,carbamorph, cufraneb, cuprobam, disulfiram, ferbam, metam, nabam,tecoram, thiram, urbacide, ziram, dazomet, etem, milneb, mancopper,mancozeb, maneb, metiram, polycarbamate, propineb and zineb; andconcurrently, prior or subsequently to the dithiocarbamate fungicide,with at least one systemic fungicide.

In an embodiment, the dithiocarbamate fungicide is mancozeb.

In an embodiment, the multi-site contact fungicide is a combination ofmancozeb and chlorothalonil.

Thus, in this embodiment, the present invention provides a method fortreating soybean rust in a host leguminous plant, wherein the methodcomprises treating the plant at the locus of the infection withmancozeb; and concurrently, prior or subsequently to mancozeb, with atleast one systemic fungicide.

The term contact fungicide as used herein for the dithiocarbamatefungicides denotes a fungicide that remains at the site where it isapplied but does not travel within the plant. Typically, thesefungicides do not show any post-infection activity.

In an embodiment, the contact dithiocarbamate fungicide may be appliedrepeatedly at the site of the infection at pre-determined timeintervals.

The term “systemic fungicide” as used herein shall denote a fungicidethat is absorbed into the plant tissue and possesses at least someamount of an after-infection activity. Preferably, the systemicfungicide of the present invention is capable of moving freelythroughout the plant. However, the term “systemic fungicide” is intendedherein to include the upwardly systemic fungicide as well as the locallysystemic fungicide.

In an embodiment, the systemic fungicide is preferably a quinone outsideinhibitor (Qol). In this embodiment, the quinone outside inhibitor isselected from an imidazolinone fungicide, an oxazolidinedione fungicideor a strobilurin fungicide.

Thus, in this embodiment, the present invention provides a method fortreating soybean rust in a host leguminous plant, wherein the methodcomprises treating the plant at the locus of the infection with at leastone dithiocarbamate fungicide selected from amobam, asomate, azithiram,carbamorph, cufraneb, cuprobam, disulfiram, ferbam, metam, nabam,tecoram, thiram, urbacide, ziram, dazomet, etem, milneb, mancopper,mancozeb, maneb, metiram, polycarbamate, propineb and zineb, orcombinations thereof with chlorothalonil; and concurrently, prior orsubsequently to the dithiocarbamate fungicide, with at least one quinoneoutside inhibitor.

The Qol inhibitors useful in this embodiment of the present inventioneffect the inhibition of complex III: cytochrome bcl (ubiquinol oxidase)at Qo site i.e. cyt b gene.

In one embodiment, the imidazolinone fungicide is fenamidone.

In another embodiment, the oxazolidinedione fungicide is famoxadone.

In another embodiment, the strobilurin fungicide is selected from thegroup consisting of azoxystrobin, mandestrobin, coumoxystrobin,enoxastrobin, flufenoxystrobin, pyraoxystrobin, dimoxystrobin,enestrobin, fluoxastrobin, kresoxim-methyl, metominostrobin,orysastrobin, picoxystrobin, pyrametostrobin, triclopyricarb,fenaminstrobin, pyraclostrobin and trifloxystrobin.

In another embodiment, the systemic fungicide of the present inventionis preferably a demethylation inhibitor (DMI).

Thus, in this embodiment, the present invention provides a method fortreating soybean rust in a host leguminous plant, wherein the methodcomprises treating the plant at the locus of the infection with at leastone dithiocarbamate fungicide selected from amobam, asomate, azithiram,carbamorph, cufraneb, cuprobam, disulfiram, ferbam, metam, nabam,tecoram, thiram, urbacide, ziram, dazomet, etem, milneb, mancopper,mancozeb, maneb, metiram, polycarbamate, propineb and zineb orcombinations thereof with chlorothalonil; and concurrently, prior orsubsequently to the dithiocarbamate fungicide, with at least onedemethylation inhibitor.

In this embodiment, the preferred DMI inhibitor is preferably a conazolefungicide selected from the group consisting of climbazole,clotrimazole, imazalil, oxpoconazole, prochloraz, prochloraz-manganese,triflumizole, azaconazole, bitertanol, bromuconazole, cyproconazole,diclobutrazol, difenoconazole, diniconazole, diniconazole-M,epoxiconazole, etaconazole, fenbuconazole, fluotrimazole,fluquinconazole, flusilazole, flutriafol, furconazole, furconazole-cis,hexaconazole, imibenconazole, ipconazole, metconazole, myclobutanil,pencoconazole, propiconazole, prothioconazole, quinconazole,simeconazole, tebuconazole, tetraconazole, triadimefon, triadimenol,triticonazole, uniconazole, perfurazoate and uniconazole-P.

In another embodiment, the preferred DMI inhibitor is preferablyselected from triflumizole, triforine, pyridinitrile, pyrifenox,fenarimol, nuarimol and triarimol.

In another embodiment, the systemic fungicide of the present inventionis a combination of at least one quinone outside inhibitor and at leastdemethylation inhibitor.

Thus, in this embodiment, the present invention provides a method fortreating soybean rust in a host leguminous plant, wherein the methodcomprises treating the plant at the locus of the infection with at leastone dithiocarbamate fungicide selected from amobam, asomate, azithiram,carbamorph, cufraneb, cuprobam, disulfiram, ferbam, metam, nabam,tecoram, thiram, urbacide, ziram, dazomet, etem, milneb, mancopper,mancozeb, maneb, metiram, polycarbamate, propineb and zineb; andconcurrently, prior or subsequently to the dithiocarbamate fungicide,with at least one quinone outside inhibitor and at least onedemethylation inhibitor.

In an embodiment, the preferred quinone outside inhibitor is astrobilurin fungicide and the preferred demethylation inhibitor is aconazole fungicide. In this embodiment, the preferred dithiocarbamate isselected from the group consisting of thiram, ziram, mancozeb, maneb,metiram, propineb and zineb.

Therefore, in this embodiment, the present invention provides a methodfor treating soybean rust in a host leguminous plant, wherein the methodcomprises treating the plant at the locus of the infection with at leastone dithiocarbamate fungicide selected from thiram, ziram, mancozeb,maneb, metiram, propineb and zineb or combinations thereof withchlorothalonil; and concurrently, prior or subsequently to thedithiocarbamate fungicide, with at least one strobilurin fungicide andat least one conazole fungicide.

In an embodiment, the preferred dithiocarbamate is mancozeb. In thisembodiment, the preferred strobilurin fungicide is selected fromtrifloxystrobin, picoxystrobin, azoxystrobin or pyraclostrobin, whilethe preferred conazole fungicide is selected from prothioconazole,tebuconazole, cyproconazole, epoxiconazole, metconazole andtebuconazole.

Thus, in this embodiment, the present invention provides a method fortreating soybean rust in a host leguminous plant, wherein the methodcomprises treating the plant at the locus of the infection with mancozebor combinations thereof with chlorothalonil; and concurrently, prior orsubsequently to mancozeb, with at least one strobilurin fungicideselected from trifloxystrobin, picoxystrobin, azoxystrobin orpyraclostrobin and at least one conazole fungicide selected fromprothioconazole, tebuconazole, cyproconazole, epoxiconazole, metconazoleand tebuconazole.

In one embodiment, the preferred strobilurin is trifloxystrobin and thepreferred conazole is prothioconazole. Thus, in this embodiment, thepresent invention provides a method for treating soybean rust in a hostleguminous plant, wherein the method comprises treating the plant at thelocus of the infection with mancozeb; and concurrently, prior orsubsequently to mancozeb, with trifloxystrobin and with prothioconazole.

In one embodiment, the preferred strobilurin is picoxystrobin and thepreferred conazole is tebuconazole. Thus, in this embodiment, thepresent invention provides a method for treating soybean rust in a hostleguminous plant, wherein the method comprises treating the plant at thelocus of the infection with mancozeb; and concurrently, prior orsubsequently to mancozeb, with picoxystrobin and with tebuconazole.

In one embodiment, the preferred strobilurin is picoxystrobin and thepreferred conazole is cyproconazole. Thus, in this embodiment, thepresent invention provides a method for treating soybean rust in a hostleguminous plant, wherein the method comprises treating the plant at thelocus of the infection with mancozeb; and concurrently, prior orsubsequently to mancozeb, with picoxystrobin and with cyproconazole.

In one embodiment, the preferred strobilurin is azoxystrobin and thepreferred conazole is cyproconazole. Thus, in this embodiment, thepresent invention provides a method for treating soybean rust in a hostleguminous plant, wherein the method comprises treating the plant at thelocus of the infection with mancozeb; and concurrently, prior orsubsequently to mancozeb, with azoxystrobin and with cyproconazole.

In one embodiment, the preferred strobilurin is pyraclostrobin and thepreferred conazole is epoxiconazole. Thus, in this embodiment, thepresent invention provides a method for treating soybean rust in a hostleguminous plant, wherein the method comprises treating the plant at thelocus of the infection with mancozeb; and concurrently, prior orsubsequently to mancozeb, with pyraclostrobin and with epoxiconazole.

In one embodiment, the preferred strobilurin is pyraclostrobin and thepreferred conazole is tebuconazole. Thus, in this embodiment, thepresent invention provides a method for treating soybean rust in a hostleguminous plant, wherein the method comprises treating the plant at thelocus of the infection with mancozeb; and concurrently, prior orsubsequently to mancozeb, with pyraclostrobin and with tebuconazole.

In one embodiment, the preferred strobilurin is pyraclostrobin and thepreferred conazole is metconazole. Thus, in this embodiment, the presentinvention provides a method for treating soybean rust in a hostleguminous plant, wherein the method comprises treating the plant at thelocus of the infection with mancozeb; and concurrently, prior orsubsequently to mancozeb, with pyraclostrobin and with metconazole.

In another embodiment, the preferred strobilurin is trifloxystrobin andthe preferred conazole is selected from cyproconazole, propiconazole ortebuconazole. Thus, in this embodiment, the present invention provides amethod for treating soybean rust in a host leguminous plant, wherein themethod comprises treating the plant at the locus of the infection withmancozeb; and concurrently, prior or subsequently to mancozeb, withtrifloxystrobin and with at least one compound selected fromcyproconazole, propiconazole or tebuconazole.

In another embodiment, the systemic fungicide of the present inventionis a quinone inside inhibitor. Preferably, the quinone inside inhibitorincludes cyanoimidazole fungicides and sulfamoyltriazole fungicides.

In an embodiment, the quinone inside inhibitor is selected fromcyazofamid and amisulbrom.

Thus, in this embodiment, the present invention provides a method fortreating soybean rust in a host leguminous plant, wherein the methodcomprises treating the plant at the locus of the infection with at leastone dithiocarbamate fungicide selected from amobam, asomate, azithiram,carbamorph, cufraneb, cuprobam, disulfiram, ferbam, metam, nabam,tecoram, thiram, urbacide, ziram, dazomet, etem, milneb, mancopper,mancozeb, maneb, metiram, polycarbamate, propineb and zineb orcombinations thereof with chlorothalonil; and concurrently, prior orsubsequently to the dithiocarbamate fungicide, with at least one quinoneinside inhibitor.

In another embodiment, the systemic fungicide of the present inventionis a succinate dehydrogenase inhibitor fungicide (SDHI). Preferably, thesuccinate dehydrogenase inhibitor is selected from the group consistingof benodanil, flutolanil, mepronil, fluopyram, fenfuram, carboxin,oxycarboxin, thifluzamide, bixafen, fluxapyroxad, furametpyr,isopyrazam, penflufen, penthiopyrad, sedaxane and boscalid.

Thus, in this embodiment, the present invention provides a method fortreating soybean rust in a host leguminous plant, wherein the methodcomprises treating the plant at the locus of the infection with at leastone dithiocarbamate fungicide selected from amobam, asomate, azithiram,carbamorph, cufraneb, cuprobam, disulfiram, ferbam, metam, nabam,tecoram, thiram, urbacide, ziram, dazomet, etem, milneb, mancopper,mancozeb, maneb, metiram, polycarbamate, propineb and zineb orcombinations thereof with chlorothalonil; and concurrently, prior orsubsequently to the dithiocarbamate fungicide, with at least onesuccinate dehydrogenase inhibitor.

It has been found that a combination of a multi-site contact fungicide,preferably a dithiocarbamate fungicide, along with a systemic fungicideselected from at least one Qo inhibitor (Quinone outside inhibitors), atleast one Qi (quinone inside) inhibitor, at least one DM inhibitor(demethylation inhibitor) or at least one SDH Inhibitor (succinatedehydrogenase inhibitors) leads to an unexpected and surprisingly goodcontrol of Soybean Rust as compared to other fungicides reported in theart.

Surprisingly, it has been found that dithiocarbamates, preferablymancozeb or combinations thereof with chlorothalonil, acts as asynergist to improve disease control and plant health of a host legumeplant infected with soybean rust when applied concurrently orsubsequently to at least two fungicides selected from Qo inhibitors(Quinone outside inhibitors), DM inhibitors (demethylation inhibitor),SDH Inhibitors (succinate dehydrogenase inhibitors), Qi inhibitors(Quinone inside inhibitors) or combinations thereof. The presentinventors believe that these combinations have never been hithertoreported in the art and many of their surprising properties never beenenvisaged. These combinations were found to possess surprisinglyimproved efficacy of enhanced disease control of Asian Soybean Rustcaused by Phakopsora pachyrhizi and/or Phakopsora meibomiae infections.These combinations were also found to improve the quality of the plantby decreasing stress and improving nutrition levels, thereby increasingthe yield of the plant that was infected with a fungicidal infection,especially with the soybean rust infection.

In an embodiment, these combinations were also found especiallyeffective against corynespora, antbracnose, cercospora, leaf spot,rhizoctonia and sclerotinia families of fungi apart from their superiorefficacy against phakopsora family of fungi.

Thus, in this aspect, the present invention provides a fungicidalcombination comprising at least one multi-site contact fungicide, afirst systemic fungicide and a second systemic fungicide.

In this aspect, the multi-site contact fungicide may be selected fromcopper fungicides, sulfur fungicides, dithiocarbamate fungicides,phthalimide fungicides, chloronitrile fungicides, sulfamide fungicides,guanidine fungicides, triazines fungicides and quinone fungicides.

The copper fungicides of this aspect are inorganic compounds containingcopper, typically in the copper (II) oxidation state and are preferablyselected from copper oxychloride, copper sulfate, copper hydroxide andtribasic copper sulfate (Bordeaux mixture).

The sulfur fungicides of this aspect are inorganic chemicals containingrings or chains of sulfur atoms and is preferably elemental sulfur.

The dithiocarbamate fungicides of this aspect contain a dithiocarbamatemolecular moiety and are selected from amobam, asomate, azithiram,carbamorph, cufraneb, cuprobam, disulfiram, ferbam, metam, nabam,tecoram, thiram, urbacide, ziram, dazomet, etem, milneb, mancopper,mancozeb, maneb, metiram, polycarbamate, propineb and zineb.

The phthalimide fungicides of this aspect contain a phthalimidemolecular moiety and are selected from folpet, captan and captafol.

The chloronitrile fungicide of this aspect comprises an aromatic ringsubstituted with chloro- and cyano-substituents and is preferablychlorothalonil.

The sulfamide fungicides of this aspect are preferably selected fromdichlofluanid and tolylfluanid.

The guanidine fungicides of this aspect are preferably selected fromdodine, guazantine and iminoctaadine.

The triazine fungicide of this aspect is preferably anilazine.

The quinone fungicide of this aspect is preferably dithianon.

In an embodiment, the multi-site contact fungicide of this aspect ispreferably selected from (a) a dithiocarbamate fungicide selected fromamobam, asomate, azithiram, carbamorph, cufraneb, cuprobam, disulfiram,ferbam, metam, nabam, tecoram, thiram, urbacide, ziram, dazomet, etem,milneb, mancopper, mancozeb, maneb, metiram, polycarbamate, propineb andzineb; and (b) a chloronitrile fungicide, which is chlorothalonil.

Thus, in this aspect, the present invention provides a fungicidalcombination comprising:

-   -   (i) a multi-site contact fungicide selected from (a) a        dithiocarbamate fungicide selected from amobam, asomate,        azithiram, carbamorph, cufraneb, cuprobam, disulfiram, ferbam,        metam, nabam, tecoram, thiram, urbacide, ziram, dazomet, etem,        milneb, mancopper, mancozeb, maneb, metiram, polycarbamate,        propineb and zineb; or (b) a chloronitrile fungicide, which is        chlorothalonil and combinations thereof;    -   (ii) a first systemic fungicide selected from a quinone outside        inhibitor, a quinone inside inhibitor, demethylation inhibitor        and succinate dehydrogenase inhibitor; and    -   (iii) a second systemic fungicide selected from a quinone        outside inhibitor, a quinone inside inhibitor, demethylation        inhibitor and succinate dehydrogenase inhibitor.

In an embodiment, the first and second systemic fungicides arepreferably different from each other.

In an embodiment, when the multi-site contact fungicide is a combinationof mancozeb and chlorothalonil, the preferred systemic fungicide is atleast one systemic fungicide selected from quinone outside inhibitor,quinone inside inhibitor, demethylation inhibitor or a succinatedehydrogenase inhibitor.

In a preferred embodiment, the first and second systemic fungicides areselected from different classes of systemic fungicides. For example:

-   -   (i) when the first systemic fungicide is a demethylation        inhibitor, the second systemic fungicide is selected from a        quinone outside inhibitor, a quinone inside inhibitor and        succinate dehydrogenase inhibitor; or when    -   (ii) the first systemic fungicide is a quinone outside        inhibitor, the second systemic fungicide is selected from a        quinone inside inhibitor, demethylation inhibitor and succinate        dehydrogenase inhibitor; or when    -   (iii) the first systemic fungicide is a quinone inside        inhibitor, the second systemic fungicide is selected from a        quinone outside inhibitor, a demethylation inhibitor and a        succinate dehydrogenase inhibitor; or when    -   (iv) the first systemic fungicide is a succinate dehydrogenase        inhibitor, the second systemic fungicide is selected from a        quinone outside inhibitor, a quinone inside inhibitor and a        demethylation inhibitor.

Thus, in this aspect, the present invention provides a fungicidalcombination comprising:

-   -   (i) a multi-site contact fungicide selected from (a) a        dithiocarbamate fungicide selected from amobam, asomate,        azithiram, carbamorph, cufraneb, cuprobam, disulfiram, ferbam,        metam, nabam, tecoram, thiram, urbacide, ziram, dazomet, etem,        milneb, mancopper, mancozeb, maneb, metiram, polycarbamate,        propineb and zineb; or (b) a chloronitrile fungicide, which is        chlorothalonil or combination thereof;    -   (ii) a first systemic fungicide selected from a quinone outside        inhibitor, a quinone inside inhibitor, demethylation inhibitor        and succinate dehydrogenase inhibitor; and    -   (iii) a second systemic fungicide selected from a quinone        outside inhibitor, a quinone inside inhibitor, demethylation        inhibitor and succinate dehydrogenase inhibitor;    -   such that (a) when the first systemic fungicide is a        demethylation inhibitor, the second systemic fungicide is        selected from a quinone outside inhibitor, a quinone inside        inhibitor and succinate dehydrogenase inhibitor; or when (b) the        first systemic fungicide is a quinone outside inhibitor, the        second systemic fungicide is selected from a quinone inside        inhibitor, demethylation inhibitor and succinate dehydrogenase        inhibitor; or when (c) the first systemic fungicide is a quinone        inside inhibitor, the second systemic fungicide is selected from        a quinone outside inhibitor, a demethylation inhibitor and a        succinate dehydrogenase inhibitor; or when (d) the first        systemic fungicide is a succinate dehydrogenase inhibitor, the        second systemic fungicide is selected from a quinone outside        inhibitor, a quinone inside inhibitor and a demethylation        inhibitor; or (e) when the multi-site contact fungicide is a        combination of mancozeb and chlorothalonil, the systemic        fungicide is at least one of a quinone outside inhibitor, a        quinone inside inhibitor, a succinate dehydrogenase inhibitor        and a demethylation inhibitor

In a preferred embodiment, the preferred quinone outside inhibitor is astrobilurin fungicide and the preferred demethylation inhibitor is aconazole fungicide. In this embodiment, the preferred dithiocarbamate isselected from the group consisting of thiram, ziram, mancozeb, maneb,metiram, propineb and zineb.

Therefore, in this embodiment, the present invention provides afungicidal combination comprising at least one multi-site contactfungicide selected from thiram, ziram, mancozeb, maneb, metiram,propineb, zineb and chlorothalonil or combinations thereof; at least onestrobilurin fungicide and at least one conazole fungicide.

In an embodiment, the preferred dithiocarbamate is mancozeb. In thisembodiment, the preferred strobilurin fungicide is selected fromtrifloxystrobin, picoxystrobin, azoxystrobin or pyraclostrobin, whilethe preferred conazole fungicide is selected from prothioconazole,tebuconazole, cyproconazole, epoxiconazole, metconazole andtebuconazole.

Thus, in this embodiment, the present invention provides a fungicidalcombination comprising mancozeb or chlorothalonil or combinationsthereof; at least one strobilurin fungicide selected fromtrifloxystrobin, picoxystrobin, azoxystrobin or pyraclostrobin and atleast one conazole fungicide selected from prothioconazole,tebuconazole, cyproconazole, epoxiconazole, metconazole andtebuconazole.

In one embodiment, the preferred strobilurin is trifloxystrobin and thepreferred conazole is prothioconazole. Thus, in this embodiment, thepresent invention provides a fungicidal combination comprising mancozebor chlorothalonil; trifloxystrobin and prothioconazole.

In one embodiment, the preferred strobilurin is picoxystrobin and thepreferred conazole is tebuconazole. Thus, in this embodiment, thepresent invention provides a fungicidal combination comprising mancozebor chlorothalonil; picoxystrobin and tebuconazole.

In one embodiment, the preferred strobilurin is picoxystrobin and thepreferred conazole is cyproconazole. Thus, in this embodiment, thepresent invention provides a fungicidal combination comprising mancozebor chlorothalonil; picoxystrobin and cyproconazole.

In one embodiment, the preferred strobilurin is azoxystrobin and thepreferred conazole is cyproconazole. Thus, in this embodiment, thepresent invention provides a fungicidal combination comprising mancozebor chlorothalonil; azoxystrobin and cyproconazole.

In one embodiment, the preferred strobilurin is pyraclostrobin and thepreferred conazole is epoxiconazole. Thus, in this embodiment, thepresent invention provides a fungicidal combination comprising mancozebor chlorothalonil; pyraclostrobin and epoxiconazole.

In one embodiment, the preferred strobilurin is pyraclostrobin and thepreferred conazole is tebuconazole. Thus, in this embodiment, thepresent invention provides a fungicidal combination comprising mancozebor chlorothalonil; pyraclostrobin and tebuconazole.

In one embodiment, the preferred strobilurin is pyraclostrobin and thepreferred conazole is metconazole. Thus, in this embodiment, the presentinvention provides a fungicidal combination comprising mancozeb orchlorothalonil; pyraclostrobin and metconazole.

In another embodiment, the preferred strobilurin is trifloxystrobin andthe preferred conazole is selected from cyproconazole, propiconazole ortebuconazole. Thus, in this embodiment, the present invention provides afungicidal combination comprising mancozeb or chlorothalonil;trifloxystrobin and at least one compound selected from cyproconazole,propiconazole or tebuconazole.

It was thus found that the addition of a dithiocarbamate fungicide to atleast a demethylation inhibitor or a quinone outside inhibitor or aquinone inside inhibitor or a succinate dehydrogenase inhibitor orcombinations thereof greatly increased the activity of the systemicfungicides over the expected disease control and expected yield.

In an embodiment, the application of the dithiocarbamate fungicide maybe prior, subsequent or concurrent to the application of the systemicfungicide. When the systemic fungicide is applied subsequently to thedithiocarbamate fungicide, such sequential application of the systemicfungicide may be within 24 hours to 4 weeks of the application of thedithiocarbamate fungicide. In the case of concurrent application, thedithiocarbamate may be tank mixed with other actives or per-formulatedmixtures may be conveniently used. The addition of mancozeb to existingcombination products greatly increased the efficacy of the knowncombinations, thereby acting as a synergist, improving the rate ofdisease control and improving the overall health of the plant.

The amount of dithiocarbamate to be applied may range from 1 kg/ha to2.5 kg/ha, preferred being 1.5 kg/ha to 2.0 kg ha.

In an embodiment, the dithiocarbamate may be applied in an effectiveamount so as to act as a synergist to the systemic fungicides of thepresent invention. However, the appropriate amounts of the fungicidesused in the present invention, whether multi-site contact fungicides orsystemic fungicides, is not particularly limiting and may beconveniently chosen by a skilled artisan.

The method of control of the present invention may be carried out byspraying the suggested tank mixes, or the individual fungicides may beformulated as a kit-of-parts containing various components that may bemixed as instructed prior to spraying.

In an embodiment, the fungicides or the combinations thereofcontemplated according to the present invention may be pre-formulatedand may be in the form of Water Dispersible Granules (WDG), WettablePowders, Suspension Concentrates, Emulsifiable Concentrate,Suspoemulsions, Capsule Suspensions etc. However, the choice of anypreferred formulation type is not particularly limiting.

Adjuvants and ancillary ingredients may be used to formulate suchpre-formulated compositions and may employ wetters, adhesives,dispersants or surfactants and, if appropriate solvent or oil and otheragriculturally acceptable additives.

In an embodiment, the present invention thus provides a compositioncomprising any of the fungicidal combinations such as herein describedalong with agriculturally acceptable excipients.

It is readily understood that the method of treatment of the presentinvention may be used on all host plants that are infected by bothPhakopsora pachyrhizi and/or Phakopsora meibomiae. Such exemplary hostplants may include soybean, Fenugreek, Kidney beans, Pinto beans, Favaor Broadbeans, Lima beans, Mung beans, Winged or Goa beans, Black-eyedPea, Cowpea or Yard-long Bean, Green peas, Pigeon Pea, Swordbean, Urd orBlack-gram etc.

As will be demonstrated in the examples, the addition of a multi-sitecontact fungicide to a systemic fungicide(s) for the treatment of ASR,greatly improved the disease control as well as improved yield. Thelower the mixture performance in the rust control, the greater theadditional benefit of the multi-site contact fungicide was seen.

The method of the present invention improves the existing diseasecontrol to an unexpectedly high degree and surprisingly improves theyield obtained. The method of the present invention also allows forgreater resistance control and decreases the amount of the actives used.

These and other advantages of the invention may become more apparentfrom the examples set forth herein below. These examples are providedmerely as illustrations of the invention and are not intended to beconstrued as a limitation thereof.

Examples

A study was conducted to determine the fungitoxicity of the multi-sitecontact fungicide, a dithiocarbamate fungicide mancozeb to Phakopsorapachyrhizi causal agent of Asian soybean rust (ASR) and the contributionof its incorporation to mixtures of strobilurin and triazole fungicides[demethylation inhibitor (DMI)+quinone outside inhibitor (Qol)].Experiments were conducted in the field in nine locations wherefungitoxicity of mancozeb to soybean rust was determined. Two doses weretested (1.5 and 2.0 kg/ha in various application numbers for mancozeb.The effect of mancozeb (1.5 kg/ha) incorporated to commercial mixtureswas also tested. The tests were conducted on soybean cultivar Monsoy9144 RR. A commercially available mancozeb 750 WDG (wettable granules)formulation was used for applying mancozeb. The combination mixtureswere used as follows:

S No. Combination used Dosage A(1) 200 g/L azoxystrobin + 80 g/Lcyproconazole 300 mL/Ha A(2) Mancozeb 750 WDG + 200 g/L azoxystrobin +1500 g/Ha + 80 g/L cyproconazole 300 mL/Ha B(1) 85 g/L pyraclostrobin +62.5 g/L epoxiconazole 500 mL/Ha B(2) Mancozeb 750 WDG + 85 g/L 1500g/Ha + pyraclostrobin + 62.5 g/L epoxiconazole 500 mL/Ha C(1)Cyproconazole 80 g/L + Picoxystrobin 200 g/L 300 mL/Ha C(2) Mancozeb 750WDG + 1500 g/Ha + Cyproconazole 80 g/L + Picoxystrobin 200 g/L 300 mL/HaD(1) Picoxystrobin 200 g/L + Tebuconazole 80 g/L 300 mL/Ha D(2) Mancozeb750 WDG + Picoxystrobin 200 1500 g/Ha + g/L + Tebuconazole 80 g/L 300mL/Ha

The percentage control of these experimental trials were noted andtabulated as hereunder:

Fungicide applied Assessment method Percent control Difference A(1)Percentage severity 36.0 — A(2) Percentage severity 68.4 +32.4% A(1) -Replicate Percentage severity 40.0 — A(2) - Replicate Percentageseverity 68.0 +28.0% B(1) Percentage severity 51.7 — B(2) Percentageseverity 71.3 +19.6% B(1) - Replicate AUDPC—Area under 55.6 — diseaseprogress curve B(2) - Replicate AUDPC 71.7 +20.7% C(1) AUDPC 47.0 — C(2)AUDPC 74.0 +27.0% C(1) - Replicate Percentage severity 44.3 — C(2) -Replicate Percentage severity 54.4 +11.1% D(1) AUDPC 68.6 — D(2) AUDPC90.2 +21.7% D(1) - Replicate Percentage severity 44.6 — D(2) - ReplicatePercentage severity 52.0  +7.4%

It was thus found that the incorporation of mancozeb increased the rustcontrol of the conventional strobilurin+conazole fungicide treatmentstandard. It was further found that the lower the mixture performance inthe rust control, the greater the additional benefit of mancozeb. It wasthus concluded that the addition of a multi-site contact fungicide suchas mancozeb acted as a synergist to the combination products registeredfor the treatment of Asian soybean rust. The addition of adithiocarbamate increased disease control and improved yield of plants.

The instant invention is more specifically explained by above examples.However, it should be understood that the scope of the present inventionis not limited by the examples in any manner. It will be appreciated byany person skilled in this art that the present invention includesaforesaid examples and further can be modified and altered within thetechnical scope of the present invention.

1. A composition comprising a fungicidal combination and at least oneagriculturally acceptable excipient, wherein the fungicidal combinationconsists of: (a) a multi-site contact fungicide selected from the groupconsisting of copper oxychloride, copper sulfate, copper hydroxide, andtribasic copper sulfate (Bordeaux mixture); (b) a first systemicfungicide that is a succinate dehydrogenase inhibitor; and (c) a secondsystemic fungicide selected from the group consisting of a quinoneoutside inhibitor, a quinone inside inhibitor, or a demethylationinhibitor.
 2. The composition according to claim 1, wherein thesuccinate dehydrogenase inhibitor is selected from the group consistingof benodanil, flutolanil, mepronil, fluopyram, fenfuram, carboxin,oxycarboxin, thifluzamide, bixafen, fluxapyroxad, furametpyr,isopyrazam, penflufen, penthiopyrad, sedaxane, and boscalid.
 3. Thefungicidal combination according to claim 1, wherein the succinatedehydrogenase inhibitor selected from the group consisting of bixafen,isopyrazam, and boscalid.
 4. The fungicidal combination according toclaim 1, wherein: (a) the first systemic fungicide is bixafen and thesecond systemic fungicide is trifloxystrobin; (b) the first systemicfungicide is isopyrazam and the third fungicide is trifloxystrobin; (c)the first systemic fungicide is boscalid and the second systemicfungicide is trifloxystrobin; (d) the first systemic fungicide isbixafen and the second systemic fungicide is picoxystrobin; (e) thefirst systemic fungicide is isopyrazam and the second systemic fungicideis picoxystrobin; (f) the first systemic fungicide is boscalid and thesecond systemic fungicide is picoxystrobin; (g) the first systemicfungicide is bixafen and the second systemic fungicide is azoxystrobin;(h) the first systemic fungicide is isopyrazam and the second systemicfungicide is azoxystrobin; the first systemic fungicide is boscalid andthe second systemic fungicide is azoxystrobin; the first systemicfungicide is bixafen and the second systemic fungicide ispyraclostrobin; (k) the first systemic fungicide is isopyrazam and thesecond systemic fungicide is pyraclostrobin; or (l) the first systemicfungicide is boscalid and the second systemic fungicide ispyraclostrobin.
 5. A method of treating soybean rust in a hostleguminous plant, comprising: applying to the plant at the locus of theinfection the composition according to claim
 1. 6. A kit comprising thecomposition according to claim 1.